lecture1 - history & introduction

ELECTRIC MOTOR DESIGN Tutorial Lectures

Instructor:

James R Hendershot

[email protected]

941 266 7631

September 2012

Mod 1 Copyright: JR Hendershot 2012 10

Introduction to motor design lectures


(37) lectures are presented covering practical design procedures for three types of electric machines which each use the same or similar stators including cores and phase windings. The first (15) lectures cover the topics that are common to all three machine types pertaining mostly to sizing, material selections & stators For IMs (induction rotors) there are (7) lectures For RSMs (reluctance synchronous rotors) there are (4) lectures For PMSM, SPM & IPM types of PM rotors there are (6) lectures An additional (5) lectures are added for general topics for thermal, mechanical, manufacturing and future challenges for machine design. These lectures are intended for engineers who have a basic understanding of the theory of electric machines. This material is intended to supplement that eclectic machine theoretical background

Electric Machine Design Course

History & Introduction of Electric Machine Types

Lecture # 1

Mod 1, Copyright: JR Hendershot 2012 12

First known Electric Motor Microscopic Bacteria Propulsion Motors Plastic model of motor


Spark Museum 1312 Bay Street Bellingham WA 98222 Tel: 360 738 3886

Early examples of electric machines and other devices

Early TESLA AC Motor


From Faraday’s law of Induction (1831)

of interactions of electric currents & magnetic fields produce mechanical forces that when properly configured produce rotation torque and power.


Tesla & others developed the uses

Electric Motor Development (last 150 years)

First motors in mid 1800’s were DC powered by poor batteries Edison employees developed practical DC machines for DC grid power Tesla patented the AC motor and the AC grid system in late 1800’s Electric motors are revolutionizing industry and products to this day Classical classroom motor for Modern classroom Dyno-Kit instruction called St Louis Motor for classroom instruction


Basic motor types for first 75 years

DC motors (wound rotor & commutated)

Battery powered

DC supply or M-G set powered

AC motors powered with 50-60 Hz grid

AC Induction & AC synchronous

AC or DC powered

Series wound commutated


Motor types from most recent 50 years

Electronically controlled for variable speed or servo

Stepping motors, VR, PM & Hybrid

PM Brushless & PM-AC synchronous PMSM

AC Induction V/Hz & flux vector controlled ACM

Switched Reluctance SRM

Reluctance Synchronous RSM Radial, Axial or Transverse flux versions



SMMA

TESLA Family Tree

Electric Machine Definitions An electric motor is a rotating machine that converts electrical energy from some external power source (can be DC or AC) into mechanical energy across the air-gap between the stationary motor part and the rotating motor part. An electric generator is a rotating machine that converts mechanical energy into electrical energy. The rotating part is driven by some external prime mover & electric power is produced across the air-gap. Both can be same machine with opposite energy flow


Magnetic Field Sources

1- Earth’s magnetic field 2- Inner planetary magnetic fields 3- Nuclear magnetic fields 4- Permanent magnet fields 5- Electro-magnetic fields 6- Super Conducting magnetic fields


Magnetic Field created by permanent magnets


Permanent bar magnet in open circuit. Flux lines extend from north pole to south pole through air or space.

Magnetic Field created by electro-magnets


Magnetic field produced by a coil with current flowing.

Magnetic field from current flowing through the coil wrapped around magnetic iron focuses magnetic flux across an air gap.

flux

N

S

Machine flux linkage overview

Two categories of electric machines: (many types in each)

Non Salient pole & salient pole machines

Salient poles exhibit mainly attractive tangential gap forces

Non-salient poles exhibit both attractive & repulsive gap forces

Torque/amp produced by magnetic flux linkage for motoring

Voltage/rev produced by magnetic flux linkage for generating


Motors with permanent magnet rotors


Original motors of this type called PM Brushless (BLDC). Evolved as outside-in (PMDC) commutated motors. Electronically commutated by switching DC voltages to each phase. Open circuit back EMF shape between square & sine. Only SPM types powered with DC phase switching. (BLDC) motors re-named to (PMSM) when driven by sine hysteresis or Id & Iq current similar to an (IM) machine. Both motors are same with different drives Back emf can be identical to original IPM versions must be Id & Iq controlled.

DC-AC Drive control chart for motor types


Motors designs included in this lecture series


(IM) AC induction machines, inverter driven (RSM) Reluctance Synchronous machines inverter driven (PMSM) Permanent magnet synchronous machines

Similar characteristics of (IM), (RSM) & (PMSM) motor types


Same stator core designs & windings Same stator manufacturing infrastructure Same use of active magnetic materials in stator Similar power inverter topologies using Id & Iq control Note: Each of the three machines types requires a special rotor design an configuration

Three rotor configurations using similar stators


IM

RSM

PMSM

Motor template cross sections by Infolytica

lecture1 - history & introduction

Documents

jr hendershot

motor design lectures

rotating motor

types of electric machines

stationary motor

basic motor types

s electric motors

powered ac motors